Tough glass composite and method

Abstract

Embodiments of a glass substrate including an alkali-containing bulk and an alkali-depleted surface layer, including a substantially homogenous composition with at least 51 mol % Al 2 O 3 are disclosed. In some embodiments, the alkali-depleted surface layer includes about 0.5 atomic % alkali or less. The alkali-depleted surface layer can be substantially free of hydrogen and/or crystallites. Methods for forming a glass substrate with a modified surface layer are also provided.

What is claimed is: 
     
       1. A glass substrate comprising:
 an alkali-containing bulk comprising Al 2 O 3  and SiO 2 ; and 
 an alkali-depleted surface layer comprising Al 2 O 3  and SiO 2 , 
 wherein:
 the alkali-depleted surface layer is substantially amorphous such that the alkali-depleted surface layer is less than 1% crystalline phase by volume; 
 the alkali-depleted surface layer has a substantially homogenous composition comprising 57 mol % or more Al 2 O 3 ; 
 the alkali-depleted surface layer exhibits a cracking probability of 50% or less for a Vicker's indentation load of 10N; and 
 the alkali-depleted surface layer is formed by thermal poling of the glass substrate. 
 
 
     
     
       2. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises about 0.5 atomic % alkali or less. 
     
     
       3. The glass substrate according to  claim 1 , wherein the alkali-containing bulk comprises an alkali-metal oxide or an alkaline-earth oxide selected from Li 2 O, Na 2 O, K 2 O, Rb 2 O, Cs 2 O, MgO, CaO, SrO, and BaO, and combinations thereof. 
     
     
       4. The glass substrate according to  claim 1  further comprising one or more mobile transition metal oxides. 
     
     
       5. The glass substrate according to  claim 4  comprising Ag 2 O. 
     
     
       6. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises Al 2 O 3  in the range from 57 mol % to 90 mol %. 
     
     
       7. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises Al 2 O 3  in the range from 57 mol % to 80 mol %. 
     
     
       8. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises Al 2 O 3  in the range from 57 mol % to 70 mol %. 
     
     
       9. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises Al 2 O 3  in the range from 57 mol % to 65 mol %. 
     
     
       10. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises a binary Al 2 O 3 -SiO 2  composition. 
     
     
       11. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer has a thickness in the range from about 10 nm to about 10,000 nm. 
     
     
       12. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer has a thickness in the range from about 10 nm to about 1200 nm. 
     
     
       13. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer has a thickness in the range from about 10 nm to about 600 nm. 
     
     
       14. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer exhibits a cracking probability of 50% or less for a Vicker's indentation load of 30N. 
     
     
       15. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer exhibits a cracking probability of 50% or less for a Vicker's indentation load of 50N. 
     
     
       16. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer has less than 0.1 atomic % of H. 
     
     
       17. The glass substrate according to  claim 1 , wherein the alkali-depleted surface layer comprises 0.5 atomic % H or less.